Effect of Extracellular pH on Motility and K⁺‐Induced Ciliary Reversal in Paramecium caudatum¹

Abstract

ABSTRACT. Paramecium caudatum, reared on bacterized hay infusions at pH 6.5 to 6.9, were washed into various buffered solutions containing 0.016 mM CaCl2 and a pH of 3.5 to 10.4. Solutions of pH 4.5 to 9.5 support strong swimming of the cells for at least 24 h. At pH values acid to the culture medium, cells show an increasing frequency of spontaneous ciliary reversal episodes (“avoiding reactions”). Uninterrupted forward swimming is usually observed over the pH range of 7.1 to 8.5, and above pH 8.5, forward motion is interrupted by circular swimming. For all pH values tested, transfer of cells to a more acidic test solution than the solutions into which they were washed (adaptation solution) usually induced short duration, periodic ciliary reversal behavior. With transfer to a more alkaline test solution than the adaptation solution, the cells shift from forward left spiralling motion to forward right spiralling motion. With decreasing pH, the cells show progressively less sensitivity to KC1 stimulation, and at pH values of less than 5.0, cells fail to show significant ciliary reversal response to any KC1 concentration tested (1 ‐ 128 mM). At alkaline pH values and higher KC1 concentrations, the cells show very pronounced ciliary reversal behaviors but usually fail to regain forward swimming behavior.

Acidification reduced growth rate but not swimming speed of larval sea urchins

“…These morphological differences could in turn reduce the neutral weight of an individual, and hence, a relatively smaller lifting force is required to propel the larva 13 30 . Second, change in pH is reported to affect ciliary activities of the ciliate Paramecium caudatum, and a decrease in pH reduced the amount of ciliary reversals and sensitivity to KCl stimulation 31 . In sea urchins, ciliary bands play a key role in swimming and swimming speeds could be maintained through reducing number of reversal, such that more of the work done by the cilia would be directed to forward propulsion.…”

Short-Term Effects of Low pH on the Microfauna of an Activated Sludge Wastewater Treatment System

“…However, Bick and Drews (1973) found that cultured populations of Aspidisca and Vorticella exhibited pH tolerances down to pH 4.5 and 5.0, respectively, while Paramecium populations declined only at pH below 4.0. Paramecium caudatum showed reduced swimming velocity and increased avoidance reactions when exposed to pH 3.6 (Doughty 1986). Flagellate protozoan populations surviving in acid mine drainage streams can withstand extremely low pH levels of less than 3.0 (Noland and Gojdis 1967).…”

On random search: Collection kinetics of Paramecia into a trap embedded in a closed domain

“…However, we have noticed a slight increase in the velocity up to 1.2 mm/s in a pH = 5 medium. [13][14][15] The motion of paramecia is strongly influenced by pH gradients in the medium and more precisely by the sign of the gradient: A paramecium swimming from a uniform neutral region at pH = 7 into a moderately acid region ͑say, at pH=6͒ has an unperturbed trajectory even if the pH front separating the two regions is sharp. The motion of the paramecium is insensitive to the change of acidity.…”